title: IL-6 mediates 11βHSD type 2 to effect progression of the mycobacterial cord factor trehalose 6,6'-dimycolate-induced granulomatous response.
abstract: Granulomatous structures are highly dynamic during active mycobacterial infection, with accompanying responsive inflammation contributing to modulation of pathology throughout the course of disease. The heightened inflammatory response coinciding with initiation and maintenance of newly developing granulomatous structures must be limited to avoid excessive damage to bystander tissue. Modulating the cellular bioavailability of glucocorticoids by local regulation of 11βHSD enzymes within responding tissue and parenchyma would allow controlled inflammatory response during infection. Mycobacterial glycolipid trehalose 6,6'-dimycolate was used to induce strong pulmonary granulomatous inflammation immunopathology. Pulmonary corticosterone was significantly increased at days 3 and 5 after administration. An inverse relationship of 11βHSD1 and 11βHSD2 message correlated with pathology development. Immunohistochemical analysis also demonstrated that 11βHSD2 is expressed in proximity to granulomatous lesions. A role for pro-inflammatory IL-6 cytokine in regulation of converting enzymes to control the granulomatous response was confirmed using gene-disrupted IL-6-/- mice. A model is proposed linking IL-6 to endocrine-derived factors which allows modification of active corticosterone into inert 11-dehydrocorticosterone at the site of granuloma formation to limit excessive parenchymal damage.
authors.affiliation: Department of Laboratory Medicine, University of Washington, Seattle, WA, USA.
authors.forename: April N
authors.initials: AN
authors.lastname: Abbott
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Welsh
authors.forename: Shen-An
authors.initials: SA
authors.lastname: Hwang
authors.forename: Paulina
authors.initials: P
authors.lastname: Płoszaj
authors.forename: Tina
authors.initials: T
authors.lastname: Choudhury
authors.forename: Sydney
authors.initials: S
authors.lastname: Boyd
authors.forename: Michael R
authors.initials: MR
authors.lastname: Blackburn
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hunter
authors.forename: Jeffrey K
authors.initials: JK
authors.lastname: Actor
mesh_terms: D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D003311:Cord Factors / Q000633:toxicity; D003345:Corticosterone / Q000032:analysis / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000276:immunology; D015769:Granuloma, Respiratory Tract / Q000201:enzymology* / Q000276:immunology / Q000473:pathology*; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000032:analysis; D011863:Radioimmunoassay; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D003311:Cord Factors; D016207:Cytokines; D015850:Interleukin-6; D012333:RNA, Messenger; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D003345:Corticosterone